What Is A Vertebrate | Definition & Classification Vertebrate

Content (Click to view)
  1. What are vertebrates?
  2. Characteristics of vertebrates
    1. Origin
    2. Body structure
    3. Classification
    4. Organs of the body
    5. External appearance
    6. Body temperature
    7. Types of respiration
    8. Examples of vertebrate animals
  3. Habitat
    1. Food & Beverage

What are vertebrates?

Vertebrates are animals that possess either a skeleton or cartilaginous bones.


This skeleton is made up of the spinal column to which the different bones of the skeleton are attached.

Vertebrates can be grouped for study in 5 subgroups:

  1. Mammals.
  2. Fish.
  3. Birds.
  4. Reptiles.
  5. Amphibians.

Although all have a spine and are considered to have common anatomical features, their external appearance varies greatly.

Its size (for example) can be tiny (a few centimeters) or measure several hundred meters and weigh many tons.

Vertebrate animals are considered to have a higher degree of intelligence and more skills than the invertebrate group.

In a manner of speaking, they are more developed or evolved animals. They have a type of organism that is somewhat more developed or evolved than the other group: invertebrate animals.

Characteristics of vertebrates


They originated in the Cantabrian explosion, at the beginning of the Paleozoic. The oldest known is the Haiouichthys, which is 525 million years old.
As a distinctive feature of this ancient vertebrate species, its jaw, skull, and skeleton all had a cartilaginous appearance.

Body structure

All vertebrates have 3 body parts:

  1. Head.
  2. Trunk.
  3. Extremities


As mentioned above, this group is subdivided, for study purposes, into 5 subgroups with well-differentiated characteristics in terms of diet, anatomy, habitat, etc. These subgroups are:

  1. Mammals
  2. Birds
  3. Reptiles
  4. Amphibians
  5. Fish

Sexual dimorphism exists in this type of animal. In other words, males and females can be distinguished. Its form of reproduction is also sexual, although fertilization can be external or internal.

External fertilization (oviparous). They're vertebrate animals that lay eggs. In other words, the calf develops outside the mother's body. For example the hen, ostrich, reptiles and many species of fish.

Internal fertilization (Viviparous). Fertilization is provided within the mother's body. For example, mammals and a great variety of fish.

Organs of the body

  1. Skin: The skin consists of the epidermis and dermis. It is, in the epidermis, that the annexes are found and it is precisely from there that the hair, nails, scales, hair or horns are born.
  2. Nervous System: They have a central and a peripheral nervous system. They also have muscles and skeletons that allow them to make movements.
  3. Circulatory system: They have a circulatory system composed of a heart and blood vessels.

External appearance

Its external appearance varies considerably, as does its size.

  1. Fish: The fish have scales and their size could be from a few centimeters to several meters.
  2. Mammals: Mammals have hair, claws, limbs with feet, hands or legs. In terms of size, they can also range from a few kilograms to several tons. In the case of aquatic mammals, instead of having clawed limbs, they have fins and no hair but only skin that covers them.
  3. Birds: Birds have feathers that, together with their wings, allow them to fly or glide.
  4. Amphibians: On the other hand, amphibians have a moist, bare skin type. In their extremities, they have very developed muscles that allow them to jump or swim.
  5. Reptiles: Finally reptiles have scales. Generally, their extremities (if they have them) are short since they are animals that crawl on the ground and this allows them to have greater speed.

Body temperature

This temperature and its variation (or not) will depend on the subgroup to which the vertebrate belongs. Thus, it is divided into two main groups: warm-blooded and cold-blooded.

  1. Hot blood. Mammals maintain an invariable type of body temperature. Within this group, there are also birds.
  2. Cold blood. Reptiles, for example, have a variable body temperature depending on the environment in which they are found. For this reason (and along with amphibians) they are said to be cold-blooded animals. In the case of fish, their body temperature is also variable. For this reason, there are fish of cold water and others of tropical water (warm).

Types of respiration

According to the classification mentioned above, two types of respiration can be indicated: by means of a pulmonary apparatus or through bronchi.

  1. Pulmonary: Reptiles have lungs. Adult mammals, birds, and amphibians as well.
  2. Branchial: On the other hand, fish and larval amphibians have gills.

Examples of vertebrate animals

Dogs are also vertebrates.

Some simple examples of vertebrate animals are:

  • Terrestrial mammals such as dogs, cats, elephants, lions, giraffes, pumas, hyenas, wolves, camels, sheep, horses, rhinoceroses, etc.
  • Primates and apes, such as orangutans, chimpanzees, gorillas, spider monkeys and humans themselves.
  • Bony fish, such as sea bream, cod, sardines, swordfish, catfish, toadfish, tuna, etc.
  • Cartilaginous fish, such as sharks or manta rays.
  • Aquatic mammals, such as dolphins, whales, seals or sea lions.
  • Birds of all kinds, such as vultures, sparrowhawks, toucans, owls, crows, hummingbirds, parrots, macaws, woodpeckers, kingfishers, pelicans, etc.
  • Amphibians such as toads and frogs, salamanders or newts.

Reptiles such as snakes, boas, crocodiles, caimans, turtles, lizards, iguanas.


As for habitat (and its adaptability) it is intimately related to the type of body temperature that the subgroup possesses.

  1. Mammals: Mammals may inhabit water or land depending on the species. Although mammals are often associated with their habitat on land, this is not always the case. For example, the whale is a marine mammal.
  2. Reptiles: Reptiles often inhabit warm or temperate areas, as their body temperature varies according to external climatic conditions.
  3. Birds: Birds can inhabit (according to their species) from cold zones (polar zones) to tropical zones. Although they find a greater variety of species in temperate, sub-tropical and tropical zones.
  4. Amphibians: Amphibians live on land and in water generally in temperate zones.

Food & Beverage

As for his food we can mention that:

  1. Amphibians: Amphibians feed on insects, worms, or other smaller animals.
  2. Mammals: They feed on other animals and vegetables. They have mouths, lips and teeth to suck the mother's milk (in the case of the young of internal fecundation) and to crush the animals that hunt or that scavenge.
  3. Birds: They have a very variable diet depending on the type of bird in question. But we can mention that all of them have beaks and lack teeth.
  4. Fish: They feed on microorganisms, smaller fish and marine vegetables.
  5. Reptiles: They are mostly carnivores and hence have tip-shaped teeth. But there are also reptiles that feed on vegetables and only have a few tiny flat teeth for that purpose.

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